This is the English language Wikipedia. Wikipedia is a multi-lingual project; as of November 2014, there were 288 Wikipedias in various languages and dialects. Each Wikipedia is assigned a two or three letter code that corresponds to its language. So, for example, the English Wikipedia's code is "en" and the English Wikipedia's Internet address is en.wikipedia.org, technically a subdomain of wikipedia.org. The codes largely come from two international standards for language codes. For full details and a sortable table of all Wikipedias, see List of Wikipedias.
Manual of StyleEdit
Like most publications, Wikipedia has guidelines that try to standardize details of its writing style to present a uniform appearance, and improve the reader's experience. Since Wikipedia generally allows anyone to edit, the guidelines are also needed to prevent the inevitable conflicts between editors with differing viewpoint on stylistic matters. Wikipedia:Manual of Style (MoS) is the main guideline, but there are many additional guidelines for specific topic areas.
The title of a Wikipedia article generally uses the version of the subject's name which is most common in the English language, as you would find it in English language reliable sources. The messy details on applying this principle are in Wikipedia:Naming conventions (use English).
National varieties of EnglishEdit
Spelling, vocabulary and sometimes grammar differ among English-speaking nations and regions. Because Wikipedia is used everywhere, it has not adopted a single variant of English as its standard, instead it tries to standardize the English used within a single article. Articles that clearly deal with one nation or region use the spelling of that region. Articles that do not have regional ties use the variant chosen when they were first written. Changing the spelling within an article without a very good reason is not allowed and is considered disruptive. The details of these rules are spelled out in Help:National varieties of English and in Wikipedia:Manual of Style#National varieties of English.
Wikipedia articles that give guidance on pronouncing their title or other words generally use the International Phonetic Alphabet (IPA). IPA is complex because it can represent the sounds of any spoken language. For an introduction to IPA designed specifically for English readers, see Help:IPA/Introduction. A concise table of the most common IPA symbols used on the English Wikipedia is found at Help:IPA/English.
Some articles contain links to audio files with pronunciation and other content. If you have trouble playing these files, see Wikipedia:Media help.
Use of non-English sourcesEdit
Wikipedia depends on outside reliable sources for verification (see WP:Verifiability). While citations to non-English sources are allowed, English-language sources are preferred over non-English ones whenever English sources of equal quality and relevance are available. See Wikipedia:Verifiability#Non-English sources.
Many articles have versions in other languages; if so the available languages are listed in the navigation area on the left of the desktop view. Sometimes these are translations, but frequently they are independently written, and many English articles were initially translated from other language Wikipedias. To request a translation or to assist if you have skills in other languages, visit Help:Translation.
For help showing snippets of text in another language in a Wikipedia article, see:
For help linking a word or phrase to an article in Wikipedia in another language, see Help:Interlanguage links.
For help showing which languages you understand on your personal Wikipedia user page, see Template:Languages.